In a separate letter to workers, BA warned that services from both Gatwick and London City airport are under threat.

With operations out of both sites suspended, quarantines imposed around the world and passenger confidence unlikely to return for years, airline bosses said: "There is no certainty as to when or if these services can or will return."

More than 1,000 of the company's 4,300 pilot jobs are on the line, according to the letter entitled “preparing for a different future”. BA has warned it may take years for traveller numbers to get back to where they were at the end of 2019.

It said: "We need to ensure that our remaining operation is efficient, flexible and cost-competitive to enable us to survive in an increasingly lean and unpredictable industry.”

Pilots union Balpa promised to fight to save every pilot job at BA as the airline prepares for a possible end to a golden age of international travel.

General secretary Brian Strutton said: The company has declined Government support claiming it is financially secure enough to survive the coronavirus crisis, so it is hard to see how these cuts can be justified.

“There are many options to ensure BA can continue its business and survive coronavirus and Balpa does not accept that job losses are the only answer. Pilots want evidence that all options have been explored fully.”

A number of airlines have applied for bespoke support from the Government. Many have now withdrawn their request and have made applications to for loans under the Treasury’s Coronavirus Large Business Interruption Loan Scheme, where so-called “squeezed middle” businesses can secure up to £25m of ultra-cheap credit from thier bank backed by a taxpayer guarantee.